Mechanical pen



FIG. 1 is a right front perspective view of a mechanical pen showing our new design;

FIG. 2 is a right side elevational view;

FIG. 3 is a right side elevational view in a retracted position;

FIG. 4 is a top plan view on an enlarged scale;

FIG. 5 is a front elevational view of FIG. 3;

FIG. 6 is a left side elevational view of FIG. 3;

FIG. 7 is a rear elevational view of FIG. 3; and

FIG. 8 is a bottom plan view thereof on an enlarged scale. 

The ornamental design for a mechanical pen, as shown and described. 